Table 19.
Summary of clearance exposure guidelines for principal CWA degradation products on surfaces (“toddler” transit passenger SRCL), and via incidental soil ingestion (both residential and industrial).a
| Residential soil |
Industrial soil |
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| CWA Degradation Product | Transit Passenger SRCL4hr Protective estimate (mg/cm2 surface; 4 h continuous exposure) | Transit Passenger SRCL24hrProtective estimate (mg/cm2 surface; 24 h continuous exposure) | Preliminary Remediation Goal (PRG) (mg/kg soil) | Outdoor Worker Preliminary Remediation Goal (PRG) (mg/kg soil) | Indoor Worker Preliminary Remediation Goal (PRG) (mg/kg soil) | |
| TDG (thiodiglycol) | 1.06 × 102 | 1.77 × 101 | 2.4 × 104 | 6.0 × 104 | 8.2 × 105 | |
| EMPA (ethyl methylphosphonic acid) | 7.08 | 1.18 | 1.7 × 103 | 4.2 × 103 | 5.7 × 104 | |
| MPA (methyl phosphonic acid) | 5.06 | 8.44 × 10−1 | 1.2 × 103 | 3.0 × 103 | 4.1 × 104 | |
| EA2192 | 1.89 × 10−3 | 3.15 × 10−4 | 4.7 × 10−2 | 6.8 × 10−1 | 1.2 | |
aRegional Screening Level (RSL) user guide disclaimer states that the RSL guidance is not mandatory, does not provide binding rules, and points out that alternative approaches for risk assessment may be more appropriate on a site-specific basis (USEPA 2009, see http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/usersguide.htm). Use of the RSLs has been accepted only by Regions 3, 6, and 9; other EPA regions have not officially approved the application of RSLs. Thus, Preliminary Remediation Goals (PRGs) other than RSLs are still in use within the remaining seven EPA Regions, and reference to PRG use is valid. Also Table 6.